Characterization Of Graphite Particle Shape In Spheroidal Graphite Iron Using A Computer-Based Image Analyzer

B. I. Imasogie, U. Wendt

Department of Metallurgical and Materials Engineering Faculty of Technology Obafemi Awolowo University, Ile-Ife, Nigeria..
Institut für Werkstofftechnik und Werkstoffprüfung Technische Universit?t Magdeburg, Germany..

DOI: 10.4236/jmmce.2004.31001                

Abstract

A procedure and specification for evaluating the degree of spheroidization of graphite in spheroidal graphite iron (SGI), using a computer-based image analyzing system has been developed as an aid to structure-property-quality assessment. Both global and feature-specific numerical indices have been programmed and implemented using a Zeiss Jenaphot 2000 projection microscope and SEM interfaced to a computer-based MACROS III analyzer and a CCD video camera. The modular procedure has been tested and used to evaluate the effect of variation in the degree of spheroidization of graphite on the 0.2 % offset yield strength for an iron series ranging from ASTM type I (fully nodular) to ASTM type II-III-IV (mixtures of nodular and compacted/vermicular graphite) and were found to indicate good correlation.

Keywords

Spheroidal graphite iron (SGI), graphite morphology, characterization, image analysis.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Fuller, A. G., Emerson, P. J., and Sergeant, G. F., 1980, “A Report on the Effect Upon Mechanical Properties of Variation in Graphite Form in Irons Having Varying Amounts of Ferrite and Pearlite in the Matrix Structure and the Use of Nondestructive Tests in the Assessments of Mechanical Properties of such Irons”, AFS Trans, No. 80-09, pp. 21-50.
[2]	Emerson, P. J., and Simmons, W., 1976, “Final Report on the Evaluation of the Graphite Form in Ferritic Ductile Iron by Ultrasonic and Sonic Testing, and the Effect of Graphite Form on Mechanical Properties”. AFS Trans. No. 76-26, pp. 109-128.
[3]	Imasogie, B. I., Afonja, A. A., and Ali, J. A., 2000, “Properties of Ductile Iron Nodularised with Multiple Calcium-Magnesium Based Master Alloy”. Mater. Sci. and Technol., Vol. 16, pp. 194-201.
[4]	Lee, S. C., and Suen, J. M., 1989, “Ultrasonic ND Evaluation of Matrix Structures and Nodularity in Cast Irons”, Met. Trans. A. Vol. 20A, pp. 2399-2407.
[5]	Fuller, A. G., 1977, “Evaluation of the Graphite Form in Pearltic Ductile Iron by Ultrasonic and Sonic Testing and the Effect of Graphite Form on Mechanical Properties, AFS Trans. No. 77-102, pp. 509-526.
[6]	Riebel, U., Kofler, V., and Loffler, F., 1991, “Shape Characterization of Crystal and Crystal Agglomerates”. Part. Part. Syst. Charact. No. 8, pp. 48-54.
[7]	Capeletti, T. L., and Hornada, J. R., 1974, “Nodular Iron Shape Factor – a New Approach to Quantifying Graphite Morphology”. AFS Trans. No. 82, pp. 59-64.
[8]	Tanaka, Y., Saito, H., Tokura, I., and Ikawa, K. 1982, “Relationship Between Some Physico-Mechanical Properties and Numerical Indexes of Graphite Shape in Compacted-Vermicular Graphite Cast Irons”. Trans. ASME, 104, pp. 60-65.
[9]	Underwood, E. E., Grebetz, J. C., and Koos, R. A., 1982, “Statistical Study of Graphite and Pearlite in Nodular Cast Iron”. Prakt. Metallogr. 19 (6), pp. 347-355
[10]	Machalikova, J., Skocovsky, P., Suchanek, V., and Sykora, P., 1991, “Quantitative Evaluation of Graphite Shape in Cast Iron”. Metallic Materials. 29 (3), pp. 174-180.
[11]	Ledbetter, H., and Datta, S., 1992, “Cast Iron Elastic Constants: Effect of Graphite Aspect Ratio”. Z. Metallkd. 83, 3, pp. 195-198.
[12]	Pundale, S. H., Rogers, R. J., and Nadkarni, G. R., 2000, “Finite Element Modelling of Elastic Modulus in Ductile Irons: Effect of Graphite Morphology”. AFS Trans. 98-102, pp.99-105.
[13]	Li, J., Lu, L., and Lai, M. O., 2000, “Quantitative Analysis of the Irregularity of Graphite Nodules in Cast Iron”. Materials Characterization. 45, pp. 83-88.
[14]	Li, J., Lu, L., Su, Y., and Lai, M. O., 1999, “Fractal-based Description for Threedimensional Surface of Materials”. J. Appl. Phys. 86, pp. 2526-2532.
[15]	Milman, V. Y., Stelmashenko, N. A., and Blumenfeld, R., 1994. “Fracture Surfaces: a Critical Review of Fractal Studies and a Novel Morphological Analysis of Scanning Tunneling Microscopy Measurements”. Prog. Mater. Sci, 38, pp. 425-474.
[16]	Imasogie, B. I., 2003, “Optimum Ca-CaC2-Mg Masteralloy Concentration Requirements in Graphite Nodularising Treatment of Cast Iron”. Materials Engineering. Vol.14, No. 1, pp. 77-86.
[17]	Weichert, R., 1989, “Charakterisierung von Partikelkonturen Mittels Fraktalen und Komplexer Fourieranalyse”. Prepr. 4. Europ. Symp. Particle Characterization. Nürnberg, 19-21 April, 1989, Vol. 1, pp. 409-420.
[18]	Clark, N. N., Diamond, H., Gelles, G., Bocoum, B., and Meloy, T. P., 1987, “Polygonal Harmonies of Silhouettes: Shape Analysis”. Part. Charact. 4, pp. 38-43.
[19]	Imasogie, B. I., 2003, “Microstructural Features and Mechanical Properties of Compacted Graphite Iron Treated with Calcium-Magnesium Based Masteralloy”. Journal of Materials Engineering and Performance, 12 (3), pp. 239-243.
[20]	Tsutsumi, N., and Imamura, M., 1978, “Proposal of the Classification of Spheroidal Graphite Form in Spheroidal Graphite Cast Iron”. Rept. Castings Res. Lab. Waseda University, No. 29, pp. 15-23.
[21]	Tsutsumi, N., and Imamura, M., and Sakuma, Y., 1979, “Analysis of the Fading Phenomena of Spheroidal Graphite in Magnesium Treated Iron Melt with Image Analyzing Computer”. Rept. Castings Res. Lab. Waseda University, No. 30, pp. 40-53.